The invention relates to a circuit breaker. More particularly, the invention relates to a circuit breaker of the type comprising a base and a cover, the base and/or cover having a rear wall portion, a front wall portion and a pair of side wall portions extending between the front and rear wall portions to define an enclosure, upper and lower rail mounting devices extending from the rear wall of the housing, one of the rail mounting devices comprising a pair of spaced-apart jaws extending from the rear wall of the housing, a calibration access aperture extending through a wall of the housing through which access is gained to a calibration device in the enclosure.
Circuit breakers of this type are known. In conventional circuit breakers however the aperture through which access is gained to the calibration device in the enclosure is generally located in a position such that the calibration may be tampered with. In some cases the calibration aperture is covered by a separate cover, however, this is not entirely satisfactory as the cover may also be removed.